Load break



May 31; 1955 H. P. SCHNEIDER LOAD BREAK 3 Sheets-Sheet l Filed Feb. 29.1952 IN V EN TOR. A. der' May 31, 1955 H. P. SCHNEIDER LOAD BREAK FilledFeb. 29, 1952 3 Sheets-Sheet 2 l v INVENToR.

HZ'orny May 31 1955 H. P. SCHNEIDER 2,709,736

LOAD BREAK Filed Feb. 29. 1952 3 Sheets-Sheet 3 ,ffy 4 INVENTOR. Hans.Schn r' United States Patent O i LOAD BREAK Hans P. Schneider, SouthMilwaukee, Wis., McGraw Electric Company, Milwaukee, poration ofDelaware assigner to Wis., a cor- This invention relates to a load breakto be used principally on an enclosed fuse cutout for electricalapparatus.

There are numerous occasions when it is necessary to inspect theelectricai lines or to do some repair work on the lines, and of course,to do so requires interrupting the current. fuse cutout when openedprovides an air gap but when a fuse cutout is opened manually it is aptto draw a large arc. This is dangerous to the safety of the lineman. Alarge arc may also burn the contact points which would lessen theeiiciency of the contacts. Therefore, it can be seen that if a way canbe devised for opening a fuse cutout without drawing an arc, it wouldeliminate a dangerous hazard to the linenien and prevent burning of thecontact points and destruction of the cutout h using.

One object of this invention is to provide an air gap in a fuse cutoutwithout drawing an arc.

Another object of this invention is to shunt the current that passesthrough the air gap between the upper stationary contact and the uppermovable contact of a fuse cutout while the door of the cutout is beingopened.

And another object if this invention is to provide a load breaksectionalizing device in which the operator may open the circuit withthe assurance that the arc will be confined to a predetermined zone inthe device and will be substantially extinguished without anypossibility of ashover.

ther objects will appear from time to time in the course of thespecification and claims.

l illustrate an embodiment of my invention in the accompanying drawings,in which:

Fig. l is a sectional view of the load break attached to the top of afuse cutout, the load break in inactive position.

Fig. 2 is similar to Fig. l showing the load break shortly after arcinterruption.

Fig. 3 is a side elevation showing a load break mounted on the top of afuse cutout.

Fig. 4 is a front elevation showing a load break mounted on the side ofa fuse cutout.

Like reference figures illustrate like parts throughout.

Referring to Fig. l, l show a fragment of a standard fuse cutout Ilconsisting of a porcelain body portion 2 with a hinged door 3. Thehinged door 3 has an eyelet handle 4 to facilitate opening. On the innerside of the cutout door 3 is attached a fuse tube 5 which moves with thedoor. A movable contact 6 extends from the upper end ot' the fuse tube 5through an opening in the door 3 to the outside of the fuse cutout, andthis conductor serves as a Contact means when the load break is beingused.

The load break 7 is mounted by means of a conductive support member dthrough an opening 9 in the upper end of the fuse cutout 1. Some cementmeans 16 is used to fasten the support member 8 to the fuse cutout. Thissupport member 8 is also connected with the power line entering the fusecutout.

The load breakf is composed of conductor elements and non-conductortubular portions and a latch which 2,709,736 Patented May 31, 1955 lCC 2operates the load break when it is tripped by the movable Contact 6extending from the door 3 of the fuse cutout.

A conductive tubular member 11 has a cap closure i2 at its outer end andat the other end it is tted into a metal sleeve 13. This metal sleeve 13is encompassed by a conductor band ltd to which the mounting conductivesupport member 8 is attached. At the opposite end ofthe sleeve t3 tromthe tubular member 11 is a iibre tube 16 which ts into a grooved portion17 of the sleeve 13. An arcing conductor ring l ts between the end ofthe fibre tube i6 and a shoulder in the sleeve 13.

A metal rod 19 is disposed longitudinally within the bre tube io. Rod 19normally serves as an electrical connection from the interior to theexterior or" the load break device by means of providing it with anarcing contact 2t) in electrical contact with resilient arms 2S incircuit continuity with sleeve 13.

Arcing contact Ztl is maintained in axial alignment with rod 19 byscrewing it into the end of a plunger 21 composed of an insulatingmaterial of plastic such as methyl methacryiate. A helical spring 22 incompression is interposed between cap i2 and the head portion 2ininteriorly of plunger 2l. circumjacent a spring aligning shaft 3S.

It is apparent that arcing contact 2d may separate from resilient arms23 under the action of spring 22 to disrupt the electrical continuity ofthe load break device, but this action is normally prevented by an axialcounterforce maintained along rod 19 by reason of it being latched.

The conductor rod i has on its outer end a head member 24 of greaterdiameter than the conductor rod i9. A notch 25 on the side of the head24 forms the means in conjunction with a latch 29 for holding theplunger 2l and rod 19 within the load break housing.

A shunt horn 25 which shunts the air gap between the upper stationarycontact and the upper movable contact of the cutout is held in rigidassociation with the bre housing 16 by means of a ferrule 27' andlocking means 2S. T he shunt horn 26 holds the latch 29 shaped to tit inthe notch 2S and held in that position by a leaf type spring The latch29 has an extension 29a which forms the tripping means for moving thelatch out of Contact with the conductor head 24.

Positive electrical contact between the slidabie conductor head 2d andferrule 27 is obtained by means of a U- shaped spring 31 anchored to theferrule and strongly pressing against head 26? as seen in Fig. l.However, when the load break device has been tripped as illustrated inFig. 2, spring 3l drops down into contact with rod 19 so that thecurrent being interrupted passes from said rod to said errule 2'7 tohorn Z6 without any air gaps being formed in the circuit. Therefore, allarcing occurs between arcing contact 2t) and arcing ring 1S during theoperation ot' the load break.

The use and operation of my invention are as follows:

In Fig. i the load break is inactive, the door of the fuse cutout isclosed and current is traveling through the fuse cutout. in Fig. 2, thedoor orc the cutout is open, the current has been shunted around the airgap between the stationary terminal and the movable contact 5 tiroughthe load break, the contacts separated, and the resulting arcextinguished by the higher air pressure within the nbre tube rushingout. This creates an air gap.

rThe mounting conductor 8 is electrically connected within the fusecutout and a conductive path exists within the load break from the band1d to the sleeve 13, to the resilient arms 23, to arcing contact 2u, tothe conductor rod 19, to the head 24 of the conductor rod i9, to thesaid shunt horn 26 with its latch tongue 29 resting in the notch 25.Consequently, when the fuse cutout door is opened the movable Contact 6reaches the said shunt horn 26 along its curved surface 25a which closesthe circuit through the load break. This contact is made before thecircuit within the fuse cutout is broken as the distance that the cap onthe end of the fuse tube travels between the contact brackets 15 isgreater than the distance between the movable contact 6 and the curvedsurfaces 26a of the said shunt horn 26.

Since the current is already shunted around the air gap between theupper stationary terminal and the upper movable contact of the cutoutbefore breaking the Contact between the fuse 5 and the contact brackets15 there is no spark over within the cutout housing as the door 3 of thefuse cutout is being opened. The current continues to travel through thefuse so that the line is protected from overload at all times.

As the door 3 is opened farther the movable contact 6 trips the latchextension 2%, moving the latch 29 out of the notch 25 which releases thesuspended assembly within the load break housing. The pressure spring Z2pushes the plastic plunger 2l to the right and the spacer 20, conductors19 and 24 ahead of it until the parts of the load break are in theposition shown in Fig. 2. The U- shaped spring El assures a conductivepath from the inner conductors 19 and 24 through the ferrule Z7 to thesaid shunt horn 26 to prevent spark over when the latch 29 is beingtripped.

After the tripping action has taken place the leaf spring 3i) returnsthe latch 29 to its former position so that it will stop the arcingcontact 20 from moving farther to the-right. Within the load breakhousing the circuit has been opened by the movement of the plasticplunger tube 21 into proximity with the fibre housing 16. The pressurecreated between the plastic and fibre being greater than the outsidepressure it will tend to push outwardly through the space 32 between theinside tubes and the ferrule 27. This pressure of gases outwardly willextinguish any arc that might occur when the circuit is opened withinthe load break. Thus, it can be seen that an air gap has been createdwithin the load break housing by moving non-conductive members into thecircuit and moving the conductive members out of the circuit.

After the repair work has been done or the inspection made, the fusecutout door can be reclosed and the circuit resumed through the fusecutout. The load break can be reused after the rod 19 with attachedplastic plunger tube 21 is pushed back against the spring 22 into thefibre tubular housing 16 and tubular member 11 respectively, to latchedposition as shown in Fig. l. Nothing is damaged in the load break byusing it. It can be put into operation many times.

My load break can be mounted on top of the fuse cutout box as shown inFig. 3 or it can be mounted on the side of the box as shown in Fig. 4.In both arrangements the mounting conductor is connected to the terminalthat enters the fuse box. The conductor strip 6 can extend through thecutout door either at the top or at the side depending upon Where theload break is placed.

With a slight change in the shape of a fuse cutout door, it is alsopossible to place this load break within the fuse box. The sameprocedure would take place. As the cutout door is opened, the movablecontact would shunt the current around the air gap between the upperstationary terminal and the upper movable terminal of said cutoutthrough the load break before the regular circuit was interrupted. lt isalso conceivable that my load break could be adapted to other forms ofcircuit interrupters.

Thus, my load break provides an effective and inexpensive device formomentarily shunting current around an air gap produced between astationary contact and a movable contact so that a circuit interruptercan be opened without dangerous arcing.

I claim:

l. A load break device in combination with a cutout, said cutoutincluding a fixed terminal, a pivotally mounted fuse tube releasablyelectrically connected thereto, and a movable Contact connected to saidfuse tube and swingable therewith, said load break device comprising acircuit interrupter biased to open circuit position and normallyelectrically connected to said fixed terminal, and latch means normallyrestraining said circuit interrupter connected to said fixed terminal inclosed circuit position, whereupon said movable contact may be swung toa rst position directly connecting said fuse with said fixed terminaland indirectly with said fixed terminal through said load break deviceto a second position connecting said fuse and load break device inelectrical series relation, and to a third position whereby said latchmeans is released to open the electrical circuit within said load breakdevice.

2. A load break device in combination with a cutout, said cutoutincluding a fixed terminal, a fuse tube releasably electricallyconnected to said iixed terminal, support means pivotally carrying andslidably embracing said fuse tube, and a movable Contact in electricalrelation to said fuse tube and swingable and slidable therewith, saidload break device comprising a circuit interrupter biased to opencircuit position and normally electrically connected to said iixedterminal, and latch means normally restraining said circuit interrupterconnected to said fixed terminal in closed circuit position, said latchmeans extending into aligned spaced relation with said movable contact,where upon said movable contact may move to a first position directlyconnecting said fuse with said fixed terminal and indirectly with saidfixed terminal through said load break device and said latch means', toa second position connecting said fuse and load break device inelectrical series relation, and to a third position whereby said latchmeans is released to open the electrical circuit within said load breakdevice.

3. A load break device for an enclosed fuse cutout, said fuse cutoutcharacterized by an insulating housing enclosing a fuse receiving fixedterminal and a fuse tube carried by a pivotally mounted door forswinging movement with respect to said fixed terminal, said load breakdevice comprising a tubular member having circuit interrupting meanstherein normally restrained in circuit closed position, a support memberelectrically connecting said fixed terminal and said tubular member, aspring biased rod means projecting from said tubular member foractuating said circuit interrupter, latch means carried by said tubularmember and engaged with said rod means for maintaining said circuitinterrupting means in circuit closed position, a movable contactelectrically connected to said fuse tube and pivotable therewith intoelectrical contact with said latch means prior to disconnection of thefuse tube from said fixed terminal, whereafter continued pivotalmovement of said movable contact will trip said latch releasing saidcircuit interrupter to circuit open position.

4. A load break device for a fuse cutout, said cutout characterized by afixed terminal and a fuse tube swingably receivable by said terminal,said load break device comprising a conductive tubular member closed atone end and a non-conductive gas evolving tubular member coaxiallyadjacent thereto, a support member electrically connecting said fixedterminal and said conductive tubular member, a plunger slidable axiallywithin said tubular members, spring means within said tube biasing saidplunger toward said gas evolving tube, an arcing contact carried by andslidable with said plunger, resilient arms normally connecting saidconductive tubular member to said arcing Contact, an arcing ringadjacent and connected to said resilient arms, a conductor rod havingone end attached to said arcing contact and another end projecting fromsaid gas evolving tubular member and including a manual reset headportion, latch means carried by said gas evolving tube normally engagingsaid rod, a movable contact connected to said fuse tube and swingabletherewith to sliding contact relation with said latch means, wherebyswinging said movable contact will divert an 5 electric current throughsaid load break device into series relation with said fuse tube.

5. A load break device for a fuse cutout, said cutout having a fixedterminal and a fuse tube swingably receivable thereby, said load breakdevice comprising a conductive tubular member and a non-conductivetubular member coaxially adjacent thereto, a support member electricallyconnected to said xed terminal and embracing said conductive tubularmember, a spring biased circuit interrupting plunger slidable withinsaid tubular members, a conducting rod connected to said plunger andprojecting coaxially from said conductive tubular member, a ferrule onsaid non-conductive tube circumjacent said rod, a substantially U-shapedspring aflixed to said ferrule and biasing said rod thereagainst, latchmeans connected to said ferrule normally restraining said plunger incircuit Closed position, a movable contact swingable with said fuse tubeinto sliding contact relation with said latch means prior to separatingfrom said fixed terminal thereby diverting an electric current throughsaid load break device, whereafter said plunger may be tripped by saidmovable contact to open the electric circuit Within said load breakdevice.

References Cited in the le of this patent UNITED STATES PATENTS1,393,344 Conrad Oct. 11, 1921 2,200,122 Rawlins May 7, 1940 2,424,126Smith, Jr July 15, 1947 2,434,315 Froland Jan. 13, 1948

